Although advancements in breast cancer treatments have resulted in improved rates of survival, a majority of women with breast cancer (BC) experience distressing symptoms during treatment, which for some, persist into survivorship. The symptoms most frequently reported among women with BC include cognitive dysfunction (CD), depressive symptoms, anxiety, fatigue, sleep disturbances, and pain, which may be collectively called psychoneurological (PN) symptoms. Inflammatory activation and epigenetic alterations have been associated with the etiology of cancer and with various chronic neurocognitive disorders. However, to date, no investigators have considered these epigenetic processes as possible mechanisms associated with the etiology of PN symptoms in women with BC. Given that epigenetic patterns have been shown to have plasticity, the further elucidation of the relationship of epigenetic alterations to the development and persistence of PN symptoms could provide foundational knowledge for the future development of predictive markers and treatments to address the epigenetic changes associated with PN symptoms in women with BC. Therefore, the specific aims of this study are to examine: 1. The frequency and severity of PN symptoms and the interrelationships among PN symptoms at each time point. 2. Levels of inflammation and to quantify the frequency and genome-wide localization of changes in epigenetic patterns across time following chemotherapy. 3. The relationships among inflammation, epigenetic changes, and the development, severity, and persistence of PN symptoms across time. To meet these aims, the proposed study will prospectively characterize PN symptoms (cognitive dysfunction; depressive symptoms and anxiety; fatigue; sleep disturbances; pain), inflammatory activation [(levels of C- reactive protein (CRP), tumor necrosis factor alpha (TNF-a), interleukin 1 beta (IL-1B), and interleukin 6 (IL- 6)], and epigenetic alterations in 75 women diagnosed with early-stage BC across 5 timepoints: prior to their receipt of chemotherapy, at the time of their fourth chemotherapy treatment, and at 6, 12, and 24 months following the initiation of chemotherapy. Epigenetic alterations will be detected by quantifying the: (1) frequency and genome-wide location of methylation; (2) expression of a histone methyltransferease, EZH2, which is a Polycomb group protein that is thought to be important for the early steps in the epigenetic decision process; and (3) telomere attrition, which can lead to alterations in chromatin compaction/gene expression. The study results may potentially deepen understanding regarding the biological processes underlying PN symptoms and lead to improved strategies for symptom management in women with BC.